System and apparatus for rapidly installed breakwater

ABSTRACT

A rapidly deployable breakwater is disclosed having a primary barrier containing liquid under pressure, and one or more overtopping barriers. The primary barrier floats at, and extends substantially below, the surface of the water, while the overtopping barriers are positioned on the primary barrier and extend substantially above the surface of the water, the combination being adapted to attenuate wave action in open water. The liquid in the primary barrier is pressurized to a level substantially greater than the pressure of the surrounding water, and such pressure may be maintained or varied during the period of deployment of the breakwater.

BACKGROUND OF THE INVENTION

The present invention relates generally to floating breakwaters, andmore particularly, to floating breakwater systems capable of rapiddeployment and retrieval, and capable of breaking or attenuating waveaction in open water. In this application, “open water” is used todenote any open water including ocean water, lake water, river water,dam water, and the like.

Breakwaters are typically either bottom-mounted or floating.Bottom-mounted structures are generally composed of large rocks(“rip-rap”) or concrete, and are massive permanent structures. Floatingbreakwaters have been used for some time as non-permanent structures atharbor entrances, swimming beaches, offshore construction, or formilitary operations. Typically, these structures include a substantiallysubmerged element which has enough inertial mass to absorb incoming waveenergy, and a buoyant element to enable the structure to float. Suchfloating structures may be moored in a relatively fixed position bylines attached to anchoring points.

Various systems have been developed to achieve a floating breakwater.Some systems have used modular concrete shells or steel frames connectedto each other by cables, with inner liners to provide buoyancy. Thesesystems enjoy the advantage of strength and durability, but are massiveand cannot easily be launched from, nor retrieved to, a dock or deck ofa vessel. Furthermore, because such systems must typically be towed totheir destination, they often lack the advantage of rapid deployment.

Thus, despite the use of floating breakwaters for some time, history haswitnessed numerous maritime incidents in which ships have run aground inhigh seas while carrying valuable cargo. In many such incidents,retrieval of such cargo by other vessels has proven difficult orimpossible due to an inability to rapidly attenuate wave action in thevicinity of the stricken vessel. Furthermore, certain vessels may needprotected anchorage, and a need has been expressed for a robust andrapidly deployable breakwater system that can be deployed in waterdepths adequate for deep draft vessels, for lightering to smallervessels or to offload vessels to other vessels or shore during highseas. Further uses for a rapidly deployable floating breakwater includeprotection of construction sites, swimming beaches, and beach erosionprotection during reclamation efforts.

Accordingly, there exists a need for a floating breakwater system whichis economical to build, which is capable of being rapidly deployed andretrieved for re-use, and which is capable of attenuating substantialwave action in open water. The present invention addresses these andother needs.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention is directed to anew and improved system and apparatus for a transportable and rapidlydeployable floating breakwater adapted to attenuate wave action in openwater. The floating breakwater includes a pressurized structure made offlexible material, which is especially configured and adapted to haveenhanced stiffness and rigidity when deployed, desirable characteristicsfor effective wave attenuation. When properly positioned and deployed inan area of undesired wave action, the breakwater of the presentinvention is capable of creating a protected area of attenuated waves inthe lee of the breakwater structure.

In a preferred embodiment of the invention, the breakwater includes aprimary barrier in the form of an elongate tubular structure of largecross sectional size or diameter with closed ends, adapted, in thedeployed state, to contain water or other liquid which is pressurized toa pressure substantially greater than that of the surrounding water. Asused herein, “substantially greater” means a difference in pressurewhich is adequate to maintain the stiffness and achieve the buckle andwrinkle resistance required for the purpose of wave attenuation. It willbe appreciated that such pressurization induces tensile forces in thematerial forming the wall of the primary barrier, and that such tensileforces enhance the wrinkle and buckle resistance of the material, thusenhancing the overall stiffness of the breakwater, which is a highlydesirable characteristic for an effective floating breakwater.Stiffening the breakwater by this means is simple and highly efficient,as it does not require additional structural material which wouldotherwise be costly and add weight to the breakwater.

In a further aspect of the invention, the breakwater may be adapted sothat, after its initial deployment and pressurization, the water withinthe primary barrier may be continually or periodically re-pressurizedthroughout the period of deployment of the breakwater in order tomaintain a substantially constant level of pressure, or to set thepressure at a different level in order to accommodate a changed seacondition.

A flotation element may be attached to or incorporated into the primarybarrier to ensure positive buoyancy of the breakwater at all times. Inaddition, overtopping barriers may be attached to the top of the primarybarrier, adapted to be buoyant in the deployed state and to attenuatewave action which would otherwise overtop the primary barrier.

The breakwater of the present invention is adapted to be expanded from acollapsed condition to an expanded condition in the deployed state. Inits deployed condition, the floating breakwater is preferably moored byat least two points along its length and prevented from drifting bymooring lines attached to the ocean bottom or other suitable fixedgeographical point. In a deployed state, it is often desirable for theprimary barrier to have a relatively large diameter and length.Diameters of between 2 feet and 30 feet may be suitable, depending onprevailing conditions.

In a further aspect, the primary barrier of the invention may beenclosed in or surrounded by a tubular jacket adapted to withstand theforces of the pressurized water within the primary barrier, and tofurther strengthen and stiffen the primary barrier. In a preferredembodiment, the jacket may be formed of circumferential and longitudinalstraps interwoven with each other.

Although a single breakwater unit may be used, a breakwater system maycomprise a plurality of breakwater units, incrementally added orsubtracted, and arranged to relate to each other in a variety ofconfigurations, depending on prevailing conditions.

The breakwater of the present invention can be used in situations wherea permanent breakwater is not feasible, available, or timely. It is alsosuitable for use in transient conditions, so that it may be temporarilyremoved if a particularly aggressive sea condition is expected, or ifseasonal conditions do not demand the protection of the breakwater. Thebreakwater of the present invention also has the advantages of beingcapable of rapid deployment from, and retrieval to, a place of storageon a reel or pallets positioned on a dock or on the deck of a vessel; ofbeing deployed and towed to a desired location, if desired; of beingrapidly expanded by filling with water; of having the ability towithstand high seas with little probability of structural failure; ofbeing unlikely to damage vessels with which it may come into contact;and of being lightweight, inexpensive, durable, transportable, andrepairable.

These and other objects and advantages of the invention will becomeapparent from the following more detailed description, when taken inconjunction with the accompanying drawings of illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a truncated plan view of a floating breakwater systemembodying novel features of the invention, showing a primary barrierwith two overtopping barriers;

FIG. 2 is a side elevational view of the breakwater system shown in FIG.1, additionally showing in enlarged cutaway section the circumferentialand longitudinal straps which may encase the primary barrier;

FIG. 3 is an end view of the view of the breakwater system shown in FIG.2, showing longitudinal straps connected to a collector plate;

FIG. 4 is an enlarged view of FIG. 3;

FIG. 5 is an enlarged cross-sectional view taken substantially alongline 5-5 in FIG. 2;

FIG. 6 is an enlarged, fragmentary detail view of the connection betweenthe primary barrier and the overtopping barriers shown in FIG. 5;

FIG. 7 is a fragmentary schematic view of a vessel launching from itsdeck a breakwater system embodying features of the present invention.

FIG. 8 is a fragmentary elevational view of the breakwater system shownin FIG. 2 deployed in water and moored to the ocean floor.

FIG. 9 is a schematic perspective view, in section, of the breakwatersystem of FIG. 2, deployed in water.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and in particular, to FIG. 1, there isshown a structure and system for one embodiment of a floating breakwater10 incorporating novel features of the present invention. Included inthe breakwater is a tubular primary barrier 20, closed at both ends,made of flexible material and adapted to be expanded from a collapsedcondition to an expanded condition in the deployed state. The length ofthe primary barrier may preferably be in the region of five to fiftytimes its diameter, to simplify manufacture and deployment. Expansion ofthe primary barrier 20 is achieved by introducing water into itsinterior cavity chamber. The surface of the primary barrier may beconfigured to have at least one sealable opening 22, adapted to bewatertight when sealed, in order to allow for the introduction of waterby a pump 46 mounted on the vessel, or, mounted on the breakwateritself. During the process of pumping, the connection between the pumpnozzle and the sealable openings 22 may be adapted to be watertight soas to enable and maintain pressurization of the primary barrier bypumping a desired amount of water into the cavity. Furthermore, one ormore vapor relief devices 21, adapted to allow air or vapor, but notliquid, to escape from the primary barrier may be installed along thetop of the primary barrier, enabling the primary barrier to be filedcompletely with liquid to the exclusion of air or vapor. In oneembodiment, the water introduced into the cavity of the primary barrieris water from the body of water in which the breakwater is deployed. Inanother embodiment, fresh water may be used if the breakwater isdeployed in the ocean, as such will provide enhanced buoyancy of thebreakwater due to the lower density of fresh water.

A preferred material for manufacturing the primary barrier 20 is acoated textile fabric, such as a waterproof, high strength polyurethanecoated polyester fabric material. Other flexible coating materials orother reinforcing fabrics, such as those made from high strength textilefiber, suitable for a marine environment also can be used. To minimizelocal stresses in the fabric, the barrier may be configured to havehemispherical or dome shaped ends. Prior to being deployed in the water,the primary barrier may be stored in a collapsed condition, mostconveniently wound onto a hydraulically powered reel or stack-folded oneither the deck of the deploying/retrieving vessel or on a dock fordeployment and towing to the installation site.

In its fully deployed state, the water in the cavity of the primarybarrier 20 is pressurized to a level substantially greater than thepressure of the water surrounding the barrier. The material embodyingthe primary barrier 20 is adapted to withstand the forces introduced bysuch pressure. It will be appreciated by those skilled in the art that,by pressurizing the water in the primary barrier 20, the material of theprimary barrier gains wrinkle and buckle resistance, thus enhancing theprimary barrier's overall stiffness. This increased stiffness hasbeneficial effects on the ability of the water-filled primary barrier 20to attenuate wave action, as it enables the breakwater to float in thewater as an effectively rigid beam.

The desired level of pressurization in the primary barrier is preferablythe pressure necessary to resist wrinkle formation in the side of thebarrier that is exposed to both current load and wave load. (This willbe the worst case, since if the current is applied in the oppositedirection to that of the waves, their two load effects will tend tocancel each other.) For any pressurized thin-walled vessel having adiameter D, that is placed in a flowing fluid current with density ρ andvelocity V, and is moored at points L distance apart, the pressure Pthat will resist wrinkling in the thin wall is given by therelationship:P≈(ρ/πg)(VL/D)²where g=acceleration due to gravity.

If the wave loading is expressed as a current with a velocity such aswould induce an amount of bending in the primary barrier equivalent tothat induced by the waves, then the velocity of the actual current(V_(current)) may be added to the velocity of the (putative) waveinduced current (V_(wave) _(—) _(induced)) to give an effective currentvelocity (V_(effective)), as follows:V _(effective) =V _(current) +V _(wave) _(—) _(induced).

Thus, in the case of a pressurized primary barrier exposed to bothcurrent and wave action forces:P≈(ρ/πg)(V _(effective) L/D)²

From this relationship it will be seen that, for a given fluid conditionand given spacing of mooring points, the pressure required to resistwrinkle formation on the side of the beam exposed to current and waveaction is inversely proportional to the square of the diameter of thebarrier.

Pressurization of the water may be achieved by pumping into the cavityof the primary barrier, via inlet ports 22, the volume of water requiredto achieve the desired pressure and level of stiffness. When fresh wateris to be used, such will generally be pumped into the cavity while thebreakwater is near the shore, whereafter the breakwater will be towedout to its desired location. It will be appreciated that once thedesired pressure is initially established, the same may dissipate due toleakage of the water from the primary barrier, or from materialstretching, or from changes in temperature. Moreover, it may be foundthat an initially established pressure must be increased to resistbuckling and wrinkling and to maintain the desired stiffness forchanging sea conditions. In such cases, pumping may be resumedcontinuously, intermittently, or at periodic intervals to maintain orvary the desired water pressure after the breakwater is initially fullydeployed and pressurized.

Moreover, it is not necessary that the desired water pressure within theprimary barrier 20 be maintained only by pumping additional water intothe cavity of the primary barrier. The water pressure may be maintainedby sealing the primary barrier in a waterproof manner or also by pumpingair or other gas into one or more inflatable pressurization tubes 23(FIG. 5) with closed ends which may be positioned within the cavity ofthe primary barrier 20. A pressurization tube 23 may be fabricated fromthe same flexible material as the primary barrier 20. Where apressurization tube is included, it will serve the additional functionof maintaining buoyancy of the breakwater 10. Furthermore, waterpressure within the primary barrier may be maintained by adding a waterreservoirs in the form of a standpipe, to the top surface of thebarrier, containing water to a level adequate to provide the desireddifferential pressure within the primary barrier.

In a preferred embodiment, it is presently believed that the breakwater10 will attenuate incoming waves in two ways. Short period, smallerwaves may be attenuated primarily by the inertial mass of the water inthe larger diameter pressurized primary barrier 20, and by overtoppingbarriers 24 which deflect wave crests from breaking across the primarybarrier. Longer period waves may be attenuated both by the inertial massof the water in the primary barrier, and by the stiffness of the primarybarrier. The stiffness of the primary barrier resists lateraldeformation (both horizontal and vertical) of the breakwater, andthereby reduces the transmission of larger waves across the breakwaterto the lee side.

In a further aspect of the invention, the strength and stiffness of theprimary barrier 20 may be enhanced by enclosing the same in a flexiblecylindrical jacket, so that the forces in the fabric of the primarybarrier are transferred to the jacket. In this aspect of the invention,the primary barrier 20 may be adapted principally to contain thepressurized water within its cavity, while the jacket may be adaptedprincipally to sustain the forces generated by the pressurized water andwave action, and simultaneously to provide increased stiffness of thebreakwater 10. This enables the primary barrier to be made from alighter weight fabric with less tensile strength, if desired. In apreferred embodiment, exemplified in FIGS. 2 and 4, the jacket maycomprise a plurality of straps, which may be longitudinal straps 28 andcircumferential straps 32 configured to enclose or surround the primarybarrier 20. The circumferential straps 32 may be interwoven with thelongitudinal straps 28, thus providing the circumferential straps with arestraint against longitudinal movement. The tightness or closeness ofthe weave may be varied. As exemplified in FIG. 4, two adjacentlongitudinal straps 28 may be configured to form a continuous loop, thuspermitting their ends 34 to be conveniently gathered at the axis of theprimary barrier 20 and attached by links 40 to a collector plate 44. Inan alternative embodiment, the jacket may consist of oppositely woundstraps (not shown in such configuration) which are oriented at anoblique angle to the axis of the primary barrier 20, rather than beingoriented parallel and at right angles to the axis. A preferredconfiguration for the obliquely wound straps is to position oppositelywound straps in helical configuration at an angle of approximately 50 to60 degrees, preferably 57 degrees, to the axis of the primary barrier.The presently preferred material from which to manufacture the straps ispolyester, but other material made from high strength textile fibersalso can be used. Both collector plate 44 and links 40 may beconstructed from suitably non-corrosive material such as galvanized orstainless steel. It will be appreciated that, while the jacket may bemade removable or permanently applied to the barrier, the jacket shouldbe connected to the primary barrier, especially during pressurization,so as to prevent dislocation of the jacket from its desired position onthe barrier. Simple stitching at intervals may be adequate to preventsuch dislocation.

It is estimated that a primary barrier 20 having a diameter of betweenabout 6 feet and 30 feet will optimally attenuate wave action in anoffshore environment, depending on prevailing conditions, while aprimary barrier having a diameter of between about 2 feet and 12 feet indiameter will optimally attenuate wave action in nearshore conditions.

Various factors and conditions may affect the overall optimalconfiguration of the breakwater. As is apparent from the relationshipset forth above, the effective current velocity and the distance betweenmooring points on the breakwater play primary roles in determining theoptimal configuration. Other factors include the amount of wave energyreduction required, the water depth, the extent to which the breakwaterprotrudes above water level, the breakwater's mass and cross sectionalshape, the type of mooring restraint, the wave height, the wave period,the wind velocity, the water temperature, and other environmentalfactors. Thus, the relationship set forth in the above formula should beseen only as a convenient guide to estimating an initial pressure forthe primary barrier. For any given breakwater, the most suitablepressure for any given sea condition may be determined by varying thepressure of the deployed primary barrier from its initial estimatedpressure until it behaves satisfactorily. As noted above, it may befound that the initially established pressure dissipates over time, orthat an increased pressure is required to deal with an increased seacondition. Such pressure maintenance or variation may be accomplished byperiodic or continued pumping and relief during the period thebreakwater is deployed.

Although the most appropriate pressure for a primary barrier of givendiameter is dependent on many variables, a preferable range ofdifferential pressures (measured as the difference between pressureinternal to the barrier and pressure external thereto at any level) maybe as follows. For barriers having a diameter of at least two feet, adifferential pressure of at least about 10 psi may be preferred; forbarriers having a diameter of at least 4 feet, at least about 3 psi maybe preferred; for barriers having a diameter of at least 6 feet, atleast about 1 psi is preferred; and, for barriers having a diameter ofat least 12 feet, at least about 0.5 psi is preferred.

It is presently contemplated that barriers configured in accordance withthe present invention may be used at differential pressures ranging fromabout 0.5 psi (for the largest diameters) to at least 30 psi, dependingon size and prevailing conditions, with pressures of about 2-10 psibeing common for larger diameter systems.

In a further aspect of the present invention exemplified in FIGS. 1-5,one or more tubular overtopping barriers 24 made of flexible materialand adapted to be expanded from a collapsed condition to an expandedcondition in the deployed state may be attached to the primary barrier20 at or near the waterline. In one embodiment, the overtopping barriersare filled with air in the deployed state and, preferably, have asmaller diameter than the primary barrier. In another embodiment, theovertopping barriers may be filled with closed cell foam, or similarbuoyant material. As they are buoyant, the overtopping barriers 24 willextend substantially above the surface of the water in the deployedstate, where they will serve to attenuate the progress of smaller wavesor the tips of larger waves which would otherwise crest over the primarybarrier and disturb the surface of the water in the lee of thebreakwater 10. The overtopping barriers 24 can be constructed to performthe additional secondary functions of adding to the stability andoverall buoyancy of the breakwater 10. Although a number of overtoppingbarriers may be used, it has been found that two are preferable. Alocation on top of the primary barrier 20 within an arc of about 30degrees on each side of the vertical centerline projected upward fromthe center of the primary barrier is considered suitable for thispurpose.

The overtopping barriers 24 may be attached in their collapsed state tothe primary barrier 20 in its collapsed state in the manner exemplifiedin FIG. 6, which shows how flexible flaps 50 may be connected to bothovertopping barrier 24 and primary barrier 20 so as to overlap with eachother. A plurality of grommets 54 may be inserted into the flaps tofacilitate attachment using flexible polyester cord. The preferredmaterial for manufacturing the overtopping barriers and the attachmentflaps is the same high strength polyurethane coated polyester fabricmaterial from which the primary barrier may be manufactured. Thisconfiguration permits the entire breakwater 10 to remain flexible in itscollapsed state, allowing it to be wound onto a reel or to be foldedonto a dock or the deck of a vessel. The overtopping barrier 24 can beattached to the primary barrier 20 or to the jacket enclosing theprimary barrier in a variety of other ways if desired.

In a further aspect of the invention, exemplified in FIG. 5, a flexibleflotation element 36 may be attached to the upper surface of the primarybarrier 20, preferably the inside surface although the outside surfacemay be desirable if water pressure in the primary barrier is likely tocompress the flotation element and reduce its buoyancy excessively. Theflotation element 36 may be made of a layer of lightweight closed-cellfoam, and is configured to ensure positive buoyancy and promote verticalorientation of the vertical centerline of the breakwater 10. Typically,the breakwater will, overall, be configured with sufficient buoyancysuch that the primary barrier 20 will just float at the tope of thenominal water surface. It will be appreciated that the flotation element36 should be sufficiently flexible to permit it to be wound onto astorage reel, or to be folded, along with the other flexible elements ofthe breakwater 10.

It will further be appreciated that, in the deployed state, the spacebetween two adjacent overtopping barriers 24 may provide a convenientprotected walkway when the breakwater 10 is made from sufficiently largebarriers, thereby providing a somewhat protected platform for operation,inspection, and maintenance of the breakwater. Where continued pumpingis required to maintain or vary the water pressure within the cavity ofthe primary barrier 20, as referenced above, it may nevertheless becomenecessary for the support vessel to leave the vicinity of thebreakwater. In this event, it may be desirable to mount a pump 46 on theupper surface of the primary barrier 20 (especially where protectiveovertopping barriers 24 are attached to the jacket or primary barrier)to maintain or vary the pressure within the primary barrier by means ofcontinued pumping. Pumping may be triggered, if necessary, by a switchconfigured to sense the pressure within the primary barrier and toswitch on the pump when the pressure falls below a designated level.Furthermore, where straps 28, 32 are used to strengthen and stiffen theprimary barrier, the same may form a conveniently rigid slip-resistantsurface between the overtopping barriers 24 to facilitate movement ofpersonnel along the length of the breakwater 10.

As to storage, deployment, and retrieval, FIG. 7 exemplifies how thebreakwater 10 may be stored on a hydraulically powered reel 70 on thedeck 72 of a vessel 74. A suitable method for deploying the breakwaterfrom the deck of the vessel may be to anchor one end at a desiredlocation in a body of water and then to power the vessel away from themooring point while unwinding from the reel and playing out thebreakwater behind the vessel. On retrieval, the primary barrier may bedrained of its liquid contents under the effect of gravity as it isrecovered upwards from the water onto a reel on a dock or recoveryvessel.

It will be appreciated that positioning a breakwater 10 at right anglesto the direction of the approaching waves achieves the longest shadow ofcalm water behind the breakwater. Depending on the prevailingconditions, it has been found that the breakwater of the presentinvention will adequately attenuate wave action when thus positioned.Alternatively, a breakwater 10 may be positioned at an angle to thedirection of the approaching waves. While this orientation provides anarrower shadow of calm water behind the breakwater, it may have theadvantage of enabling the breakwater to attenuate more energetic waveaction. Whatever length is used for each breakwater unit, it may bedesirable to attach a number of breakwaters 10 to each other end-to-end,to form an elongated breakwater system which may exceed 1000 feet inlength. In a variation of this aspect, the breakwaters may be positionedto form an arc around a specific point of interest. Alternatively, aseries of parallel breakwater units may be positioned in staggered,shingle-like fashion, in the path of the oncoming waves. In a furthervariation, a breakwater system may include a plurality of barriersarranged as a “V,” pointing into the oncoming waves, or as a “λ”(lambda) with the long leg presenting a straight barrier positioned atan angle to the path of the oncoming waves. The ideal orientation, ineach case, is determined by wind, current and wave conditions.

As noted above, it is estimated that a primary barrier 20 having adiameter between about 6 feet and 30 feet will optimally attenuate waveaction in an offshore condition, while a primary barrier having adiameter between about 2 feet and 12 feet will optimally attenuate waveaction in a nearshore condition. Suitable corresponding tubularovertopping barriers for such configurations will have a size of about 3feet to 6 feet and about 1 foot to 4 feet in diameter, respectively.When finally positioned as desired, each breakwater structure 10 may bemoored to the bottom, as exemplified in FIG. 8, by means of mooringlines 76, 76′, 76″, 76′″ attached to mooring attachments 48 on thebreakwater, and any suitable anchoring means, either on a buoy 78 or onthe ocean floor. The buoy may itself be anchored with a mooring line 80to the ocean floor. Mooring attachments 48, exemplified in FIGS. 1, 2and 4, may be constructed from suitable non-corrosive material such asgalvanized or stainless steel. In addition to mooring the breakwater byits ends, additional intermittent mooring lines 76″ may be attached tothe breakwater intermediately between the ends, attachment beingeffected by using an appropriate load spreading attachment system (notshown). The mooring lines serve to maintain the desired location andorientation of the breakwater relative to the approaching waves.

FIG. 9 exemplifies the operation of the breakwater system of the presentinvention. Waves reaching the breakwater are attenuated by the inertialmass of the primary barrier, and any cresting over the top of theprimary barrier is reflected or attenuated by the overtopping barriers,providing an area of relative calm in the lee of the breakwater.

The breakwater of the present invention has the primary advantage ofmaintaining an enhanced stiffness through pressurization of its fluidcontents, so that the breakwater may act as a rigid beam in the water,capable of absorbing and attenuating wave action. Other advantagesinclude being economical in that it is easy to build, to transport, torapidly deploy and retrieve, to repair, and to store. It may be madeprimarily from inexpensive, durable fabric, which, being lightweight andflexible, is unlikely to cause substantive damage to vessels even inelevated sea condition conditions. Indeed, the breakwater may serve theadditional function of buffering ships from colliding with maritimeobjects, and a vessel would be able to moor alongside the breakwaterwithout the need for additional fendering. The breakwater may bepressurized to maintain a desired level of stiffness to reduce waveaction. The internal pressure of the primary barrier 20 may becontrolled as necessary to provide the optimum wave suppression for agiven condition. The materials embodying the breakwater may all becorrosion resistant materials that have demonstrated long-lifecapabilities both in the stored and deployed environments. Byfabricating the breakwater as a continuous structure, frequent jointscan be avoided.

It will be apparent from the foregoing that, while particular forms ofthe invention have been illustrated and described, various modificationscan be made without departing from the spirit and scope of theinvention. For example, while the drawings of the Figures illustrateprimary barrier 20, overtopping barrier 24, and pressurization tube 23each having a circular cross section, the exact cross sectional shape ofthese elements can be varied, and may in each case assume any crosssectional shape capable of performing the element's described function.Accordingly, it is not intended that the invention be limited, except asby the appended claims.

1. A breakwater structure to be moored in open water at a selectedlocation to attenuate wave action for a desired period of time,comprising an elongated primary barrier formed of a flexible materialand having an enclosed interior cavity, said barrier being adapted tofloat in open water and to contain a liquid within said cavitypressurized to a level substantially greater than the pressure of thesurrounding open water, wherein the pressurized liquid provides thebarrier with enhanced stiffness and resistance to deformation by waveaction. 2-46. (canceled).